Muffler partition assembly



United States Patent O 3,498,407 MUFFLER PARTITION ASSEMBLY Eldred G. Straw, Grass Lake, Mich., assignor to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed Sept. 26, 1967, Ser. No. 670,575 Int. Cl. F01n 7/18 U.S. Cl. 181-61 Claims ABSTRACT OF THE DISCLOSURE A tubular shell in a mutfler is tightly secured to a transverse partition by forming a large radius neck in the partition and using the shell as a forming punch to enlarge the neck so that it tightly grips the shell, nibs on the shell engaging the butt end of the neck to act as a positive stop against withdrawal.

BRIEF SUMMARY OF THE INVENTION DESCRIPTION OF T'HE DRAWINGS FIGURE 1 is a longitudinal cross-section through a typical automotive mufiler embodying the invention;

FIGURE 2 is an enlarged view partly in section and partly -broken away of the spit chamber and partition prior to assembly;

FIGURE 3 is an end view as taken along the line 3-3 of FIGURE 2 showing the preferred manner of forming the chamber.

DESCRIPTION OF THE INVENTION Referring to FIGURE 1 the muffler 1 has a tubular shell 3, preferably of oval cross-section, which may be surrounded by insulating layers of asbestos 5 and metal 7. The opposite ends of the shell 3 are closed by headers 9 and 11 which are interlocked with the ends of the shell 3 in rolled joints 13 and 15.

An inlet 15 extends through and is spot welded to an annular neck 17 in the inlet header 9 and an outlet tube 19 extends through and is spot welded to an annular neck 21 in the outlet header 11. The tube 15 includes an upstream section that extends through annular neck 23 in a partition 25 that eXtends transversely across the shell 3 as well as a down-stream section 25 which is supported at one end in the up-stream section of tube 15 and at its outlet end in an annual neck 27 that is formed in the partition 29 that extends transversely across the shell 3. The partitions 25 and 29 together 'with partitions 31 and 3-3 divide the interior of the shell 3 into longitudinally separated chambers 35, 37, 39, 41, and 43. 'Ihe tube 15 opens into the chamber 39. This chamber s connected to the chamber 35 -by an intermediate flow tube 45 which is supported at opposite ends in annular necks 47 and 49 in the partitions 25 and 29.

The outlet tube 19 includes an up-stream section 51 supported in an annular neck 53 in the partition 25 as well as in a neck 55 in the partition 31. The down-stream end of tube section 51 is supported in the end of a bushing 57 which is a part of the tube 19 and which is supported in the annular neck 59 in the partition 33.

ICC

It is apparent that the path of gas flow through the mufiler 1 is through the tube 15 into the chamber 39; from chamber 39 through tube 45 into the chamber 35; and from chamber 35 through the tube 19 to the tailpipe (not shown). To assist in removing sound from the exhaust gases as they pass through these tubes, the chambers 41 and 43 are connected to the cross-over chamber 39 by means of a tuning tube 61 which is supported in neck 63' of the partition 31 and necks 65 and 67 'formed in the partition 33. The chambers 41 and 43 thus act as compound resonators to attenuate relatively low frequencies of sound in the gas.

The intermediate tube 45 is louvered throughout its length so that gas flowing through it communicates with the chamber 37 whereby intermediate and high frequencies are attenuated. Similarly the outlet tube section 51 has a patch of louvers 69 opening into the chamber 37.

The higher frequencies, roughness, scratch, and spit are attenuated by a spit chamber construction comprising louver patches 71 and 73 in the inlet tube construction 25 which open into closed chambers formed by means of a tube 75 that surrounds the tube section 25 and is attached to it.

This invention is concerned with the spit chamber construction associated with a louver patch 77 formed in the outlet tube section 51 and which includes the shell 79 that is mounted on the tube section 51. Preferably the shell 79 is cylindrical and concentric with the tube 51 and is attached to it at opposite ends by a pinching process which involves squeezing the ends of the shell 79 into four U-shaped folds 81 so that the metal between the folds is reduced in diameter as seen at 83 to tightly contact and grip the tube 51 in a gas tight manner. The left end Sections 83 are spotwelded to the tube as indicated by the x's.

At final assembly the shell 79 is supported in and extends through an annular neck 85 in the partition 29. In the process of pinching the folds 81 the metal tends to bulge outwardly in dimples as seen at 87. These dimples are sized so that they are no longer than about .060 in diameter than the diameter of the shell 79. They engage the end of the annular neck 85 and provide a positive stop against withdrawal of the shell 79 back through the neck which 'Would occur to the left in FIGURE 1.

It is desired to minimize spot welding of the shell 79 to the parts with which it is in contact including the partition 29. A tight fit without spot welding is obtained by special formation of the neck 85 and assembly of the partition 29 with the shell 79. This includes the initial formation of the neck 85 as an annular flange 85a (FIG URE 2) which has a radius at the corner of the neck and partition that is preferably about twice as large as the radii used on the various other annular necks such as 23, 27, 53, etc. The inner diameter of the neck 85a is smaller than the outer diameter of the shell 75. Accordingly, in a sub-assembly operation when the shell 79 mounted on the tube 51 is pressed through the neck 85a the latter will increase in diameter and reduce the radius at the corner of the neck so that the final form as seen in FIGURE 1 is substantially like that of the other necks. Because of the larger radius the neck 85a acts as a funnel and hinge to receive the shell 79 when it is pressed in place and the shell stifened by its connection to tube section 51 acts as a forming punch for shaping the neck. The assembly is performed without collapsing of the partition, and the shell and partition are securely united Without need for spotwelding. Furthermore, the method of assembly eliminates the need for a sizing operation on the neck.

Modifications may be made without departing from the spirit and scope of the invention.

What I clam is:

1. A muffler for silencing sound in flowing gases comprising a housing having a partition therein, said partition having an annular neck extending at substantially a right angle to the plane of the partition and defining an opening, a gas flow tube in said housng having a substantially uniform diameter cylindrical shell of larger diameter than the tube around a porton thereof and secured thereto, said tube being of less diameter than said neck and said shell having a larger diameter than does the neck pror to assembly of the mufiler, said neck being funnel shaped prior to assembly, said shell extending through said neck and 'being in press fit engagement with the neck and said press fit engagement tightly securing the shell to the partition.

2. A muflier as set forth in claim 1 including nibs formed on the shell to engage the end of the neck and act as positive stops against withdrawal.

3. A mufller as set forth in claim 2 wherein the shell has U-shaped folds in the ends thereof to tightly clamp it to the tube and said nibs are formed in said folds.

4. The method of making a muiler which comprises forming a partition having an annular neck with a large radius at the corner between the neck and partition, said neck definng a funnel-shaped opening, fixedly attaching a cylindrical shell to a gas flow tube, said shell being substantially larger in diameter than said opening, forcing 25 vide a tight press fit between the neck and shell to mechanically unite the shell and partition.

5. A method as set `forth in `claim 4 wherein the shell reduces the radius of the neck by about one half.

References Cited UNITED STATES PATENTS 1,907,656 5/1933 Oldberg f 181-353 2,047,443 7/ 1936 Starkweather et al. 2,112,964 4/1938 MacKenzie 181-353 2,357,791 9/1944 Powers 181-54 2,367,753 1/1945 Buck 181-353 2,772,034 11/ 1956 iRichmond. 2,922,485 1/ 1960 Muller 181-54 2,928,633 3/1960 Holmes et al. 3,209,438 10/1965 Brown 29-157 3,242,558 3/ 1966 Selig. 3.289,786 12/ 1966 Powers 181-54 F OREIGN PATENTS 892,780 3/ 1962 Great Britain.

ROBERT S. WARD, JR., Primary Examiner U.S. Cl. X.R. 

